Abstract Scope |
Sustainable development comprises actions to reuse glass fractions not recycled in the original articles, including the obtainment of new binders, according to alkali activation, in turn causing partial dissolution of fine powders and condensation of surface products. Gels with a stable network structure are formed by selection of waste glass. As an example, calcium-free boro-alumino-silicate glass, from dismantled pharmaceutical vials, with alkali hydroxide solutions at low molarity (not exceeding 3 M). The attack promotes glass hydration, followed by condensation, with limited alkali inclusion in the gel, owing to their separation as soluble carbonates. Soda-lime glass, prone to formation of less stable hydrated calcium silicates, leads to stable gels when coupled with natural glassy materials, in form of volcanic ash. Glass-derived binders exhibit a strength-to-density ratio comparable to that of gypsum and lightweight concrete and offer a distinctive end-of-life option, being converted into highly porous glass and glass-ceramic foams upon firing. |